1998 JAGUAR X308 SOLENOID

clos
ed outlet valves.
Traction Control
Trac

tion control has the same capabilities as ASC but with th
e added ability to actuate the brakes of the spinning wheel.
This enhances ASC by improving acceleration particularly on surfaces with uneven friction , e.g. one wheel on ice the other
on tarmac.
When wheelspin occurs, brake line pressure to the slipping wheel is generated, to operate that wheel's brake. The BCM
achieves this by closing the cut-off solenoid valve and oper ating the hydraulic pump. Brake fluid is then drawn from the
reservoir through the non-actuated mast er cylinder to the brake caliper.
A 'TRAC' amber warning light flashes on the instrument panel when the system detects a spinning wheel.
The traction control system uses a brake control modulator with nine solenoid valv es: four normally open inlet valves and
four normally closed outlet valves and one special isolating va lve. The outlet valves control the brakes of each each rear
wheel individually on the traction control system.
Rear Wheel Speed Senso
rs and ABS/TCCM Circuit Diagram

Pinpoint tests

W
S
S circuit: short
circuit to power
WSS f
ailure
C1
175Left -hand re
ar wheel speed
sensor (WSS) circuit failure
W S
S circuit: open
circuit
WS
S circuit: short
circuit to ground
W S
S circuit: short
circuit to power
WSS f
ailure
F
or l
eft-hand rear WSS test
s. GO to Pinpoint Test E.
C1267Modulat or valv
e failure
Supply volt
ages
to valve
solenoids or sensors out of range
Fo
r power and ground tests. GO to Pinpoint Test
A.
B1342CAN co
mmunication circuit
failure
CAN :
open circuit fault

CAN:
short circuit to
ground
CAN :
short circuit to
power
Fo
r CAN tests. GO to Pinpoint Test
F.
B1676Supply volt
age out of range
Supply voltage:
too
low
Supply volt age:
too
high
Check fo
r DTCs indicating a charging system fault.
Rectify as necesssary.
PI
NPOINT TEST A : MODULE
POWER AND GROUND SUPPLIES
TES
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
A
1
: CHECK THE POWER SUPPLY FUSES
Make sure the igniti
on is turned off. 1
Chec
k fuses 04, 16 and 18 of the engine compartment junction box.
2
Are th
e fus
es in good condition?
Yes GO to A2
.
No
Install a new f
use as
necessary. Check the syst em for normal operation. If the fuse fails again,
check the circuit for a short circuit to ground. Refer to the electrical guides.
A2: CHECK THE PERMANENT
POWER SUPPLY (1) TO THE MODULE
Disc

onnect the ABS module connector, LF27.
1
Measure the voltage between LF
2
7, pin 09 (NR) and ground.
2
Is the vol
t
age greater than 10 volts?
Yes GO to A3
.
No Re
pair the circuit between the engine compartment
junction box, fuse 16, and LF27 pin 09. Refer to
the electrical guides. Clear the DTC, check for normal operation.
A3: CHECK THE PERMANENT
POWER SUPPLY (2) TO THE MODULE
Meas
ure t
he voltage between LF27, pin 25 (NW) and ground.
1
Is the vol
t
age greater than 10 volts?
Yes GO to A4
.
No
Re
pair the circuit between the engine compartment ju
nction box, fuse 18, and LF27 pin 25. Refer to
the electrical guides. Clear the DTC, check for normal operation.
A4: CHECK
THE IGNITION POWER SUPPLY TO THE MODULE
Make sure the ignition is on. 1
Measure the
voltage between LF 2
7, pin 20 (WU) and ground.
2
Is the vol
t
age greater than 10 volts?
Yes GO to A5
.
No Re
pair the circuit between the engine compartment ju
nction box, fuse 04, and LF27 pin 20. Refer to
the electrical guides. Clear the DTC, check for normal operation.
A5: CHECK
THE GROUND SUPPLY TO THE MODULE

Steering System - General Inform
ation - Steering System
D
iagnosis and Testing
I

nspection and Verification
1.
1. Verify t
he customer concern by driving the vehicle.
2. 2. Visually inspect for obvious signs of mechanical or electrical damage.
Mec
hanical Inspection Chart
Electrical Inspection Chart
Mechanical Checks
Incorrect
tire pressure, loose whee
l nuts, incorrect wheel alignment
Loose ti
e-rods
Loose dam

per and spring assemblies or ball joint
Loose s

teering column shaft universal joints
Loose pinc

h bolts on steering column shaft
Loose steeri

ng gear assembly
Check f

or external damage to the steering gear.
- Damaged tie-rods
-
CAUTION: If a steering gear assemb ly is returned under warranty with leaking seals, but there is also
damage to the steering gear boot/boots the steering gear warranty will be invalid. This is due to the steering
gear seals being damaged due to fore ign materials entering the steering gear boot and damaging the steering
gear seals thereafter.
Damaged steering gear boot
Damaged accessory driv
e belt
Bin

ding or misaligned steering co
lumn, pump or steering gear
Incorrect fluid
level
Hose leaks o

r line restrictions
Hose fou

ling bodywork
El

ectrical Checks/Tests
Make sure all

connectors are in plac
e (steering gear Servotronic solenoid and steering control module (SCM) - if
applicable)
Make su
re all the fuses are in place and not blown
D

ISCONNECT the steering gear transducer
and the steering should become heavy
TEST e
lectrical values:
- Power Supply to the SCM = 12 Volts
- Steering gear transducer resist ance 7.0 to 7.5 Ohms is normal
(
limits: less than 5 Ohms and greater than 9 Ohms would

be declared unacceptable)

- Steeri
ng gear transducer voltage = 6 Volts
- Steering gear transducer cu rrent = 840 mA at 0 mph reducing to 0 mA at maximum speed

The rotary distri
butor and control sleeve turn relative to ea
ch other, forming the unequal restrictions which create the
differential pressures to operat e the rack piston; the displacement of the di stributor and sleeve being controlled by the
elastic deformation of a torsion bar which is concentric with the pinion and valve. Refer to Positive Center-Feel Torsion Bar
in this sub-sectio n.
The hydraulic reaction piston moves axially, relative to th e rotary distributor, and is connected to the control sleeve by a
three-bearing helical screw. Pressure applied either side of the hydraulic reaction piston is translated into a rotational force
which increases steering effort. For detail s of Servotronic speed-sensitive steering control, refer to Servotronic Control in
this sub-section.
When the vehicle is travelling straight ah ead, the valve restrictions are balanced, thus providing equal pressures on either
side of the rack piston. When load is a pplied at the steering wheel, the two halves of the control valve (rotary distributor
and control sleeve) are displaced making the restrictions unequa l. The resulting differential pressures on either side of the
rack piston, assist the steering rack to mo ve to left or right. As the turning load is removed, the pressures equalize again
and the steering return s to the straight ahead position , aided by suspension geometry.
Serv
otronic Control

P a
rts List
The Servotronic system provides steering assistance which is pr oportional to vehicle speed. It comprises the steering control
module, and Servotronic valve forming part of the hydraulic control valve assembly.
The Servotronic valve is an electro-hydrauli c device with a variable orifice, which varies in size according to the position of a
needle valve. The needle valve is controlled by a solenoid in response to a variable current input from the steering control
Ite
m
Part
Number
Descr
iption
1—Vehi
cl
e speed input
2—Steeri
ng control
module
3—Servotronic valve
4—Hydraulic

control valve housing
5—PAS stee
rin
g pump
6—Batt
ery

The te
lescopic slider provides driver crash
protection by retracting automatically in the event of an accident; it is clamped in
position to a preset torque.
The motorized upper steering column has the following serviceable parts:
Igniti
on switch assembly.
Igni
ti
on key interlock solenoid.
Ti
lt
motor assembly.
Reach motor assembly.
Manu al Upper Column Assembly


Ite
m
Par
t
Number
De
scr
iption
1-L
o
wer mounting bracket
2-Crash tube
3-Harnes
s c
onnector bracket
4-Tilt motor

5-Reach m
otor
6-Upper
moun
ting bracket
7-Ignition switc
h
(hidden)
8-Igni
ti
on key interlock solenoid
9-S
t
eering wheel mounting shaft
It
e
m
Par
t
Number
De
scr
iption
1-Upper
cowl
2-Lower cowl
3-Colu
mn tilt adjustment lever

4-Col
u
mn reach adjustment lever
5-Di
mm
er switch
Motorized Upper Co
lumn Components

Is adjustable for both til
t and reach.
Has ca

ble operated reach adjustment, using a rack an
d wedge, with approximately 16 latched positions.
Has si
x latched tilt positions steppe
d at approximately 3° intervals.
Has an u
nlatched top tilt position, allowing the column to be
pulled down to engage the first detent without using the
tilt lever.
Has an instrument li
ghti
ng dimmer switch installed on the left-hand side of the lower cowl.
Manual Upper Column Components

The telescopic slider provides driver crash protection by retracting automatically in the event of an accident; it is clamped in
position to a preset torque.
The manual upper steering column has the following serviceable parts:
Igni
tion switch assembly.
Igni

tion key interlock solenoid.
Bowden

cable and lever assembly.
It
em
Par
t Number
De
scription
1-L

ower mounting bracket
2-Crash tube
3-Harnes

s connector bracket
4-Upper

mounting bracket
5-Ignition switc

h (hidden)
6-Igni

tion key interlock solenoid
7-S

teering wheel mounting shaft


The manu
al upper
steering column:

E
ngine Management System Components
Electronic Throt
tle
The
electronic throttle assembly, in resp
onse to signals from both the driver and the ECM, adjusts idle speed, sets the
throttle valve to the position requested by the driver's accelerator / throttle pedal, cruise and traction control, power
limitation and catalyst warm-up.
Mass
Air Flow Meter
The sensor i
s located in the air flow mete
r assembly and outputs an analogue voltag e to the ECM. This sensor measures air
flow into the engine inlet system and is calibrated to measure kg / hour.
In
take Air Temperature
Th
e intake air temperature sensor is loca
ted in the air flow meter assembly and outputs an analogue voltage to the ECM.
The ECM will substitute a default value eq ual to 50°C should this sensor fail.
Fuel Injectors
The eigh
t bottom fed fuel injectors are located in the fuel rails. Th
e fuel injectors are electromagnetic solenoid valves
controlled by the ECM. The pulse time for the injector combined with the fuel pr essure determines the volume of fuel
injected to the manifold.
Fue
l Delivery
The fu
el pump provides fuel to the fuel rail where the circulat
ing pressure is controlled by a pressure regulator valve; excess
fuel is returned to the fuel tank.
The pressure regulator valve is controlled by manifold depression so that fuel delivery pressure is maintained at
approximately 3 bar above manifold pressure.
Fuel Pump
Relay
The ECM controls thi

s component for normal
engine running. The security system may disable this relay via communication
with the ECM.
Fuel Lev
el Sensing
The tank fuel

is measured by the fuel le
vel sensor . This signal is used by the ECM as an in put to certain diagnostics.
Eva
porative Valve
Excess vapour

formed in the fuel tank is
absorbed into the evaporative emission pu rge control canister. While the engine is
running, the fuel absorbed in the canister is gradually purged back into the engine. The rate of purging is governed by
engine operating conditions and vapour concentration level. Operating conditions which affect the purge rate are:
2—Purge
valve
3—Engine

torque reduction
4—E

lectronic throttle assembly
5—Coo

ling fans
6—Ignition amplifier driver
7—Engine overspeed
8—Cli

mate control compressor clutch
9—O

BDII information (J1962, CAN, ISO)

10—F
uel pump relay
11—Heat

ed oxygen sensor
12—Vari

able valve timing
13—MIL sw

itching



ECM Out
puts
It

em
Par
t Number
De
scription
1—Exhaus

t gas recirculation

Speed an
d load
Coo
l
ant temperature
Ti
me el
apsed from start up
Cl
osed l
oop fuelling
Determination of the vapour concentration is made by stepped opening of the EVAP valve and subsequent monitoring of the
fuelling correction. This function is performed prior to purging, so that at the onse t of purging the EVAP valve can be set to
the optimum position. Should the ECM be unable to determine the concentration before purging, a default value is
employed, which is then modified whilst purging is in progress.
When the purging process is operational th e ECM modifies the basic fuelling calculation to maintain the correct air / fuel
ratio.
Purging is inhibited during fuel cut-off and stability / traction control intervention.
Coolant Temperature Sen
sor
Th
e
sensor outputs a voltage to the ECM which decreases as temperature increases.
Cooling Fans


In response to engi
ne coolant temperat
u
re and climate control system demand, the ECM will energize the cooling fans.
Climate Control Compressor
The E
C
M will allow the compressor clutch to be engaged if th
e engine temperature and load demand are normal. Should the
driver require maximum engine powe r or the coolant temperature be high, the request will be denied.
Cranking Signal

The ECM reacts to a signal fr
om th
e Body Processor Module (BPM) when the starter motor relay is energi
zed. This signal is
used to trigger starting, fu el and ignition strategies.
Engine Speed and Cranksh
aft Position
Engine
speed and cran
k position are moni
tored by a sensor which is mounted on the cylinder block (flywheel housing)
behind the crankshaft drive plat e. It indicates rotational speed to the ECM in the form of 12 pulses per crank revolution.
Engine speed is used for synchronization of fuel an d ignition systems, as well as other functions.
Camshaft Position
The ca
mshaft position sensor is mounted at
the rear of Bank 2 cylinder head on the inlet side and provides one signal every
720 degrees of crankshaft rotation. The signal, in conjunction with the signal from the crankshaft position sensor, indicates
to the ECM that the piston of cylinder 1A is approaching TDC on the compression stroke.
Variable Valve
Timing (Where Fitted)
By energi
si
ng a solenoid to allow the pass
age of pressurized oil on each of the inle t camshaft drives, the ECM can vary by a
single stepped amount, the relati ve timing of the inlet valves.
Ign
ition
Ignit
i
on spark is produced by
individual on-plug coil units.
There are two ignition amplifiers; module #1 drives coils 1A, 2B, 3B and 4A, whilst module #2 drives coils 1B, 2A, 3A and
4B. The ECM controls the amplifiers.